264 



INTESTINAL DIGESTION. 



zelius found in the healthy human faeces, 73-3 parts of water and 26-7 parts 

 of solid residue. The average of seventeen observations by W^ehsarg was 

 precisely the same. In the observations of Wehsarg, the mean quantity of 

 solid matter discharged in the faeces in the twenty-four hours was 463 grains 

 (30 grammes), the extremes being 882-8 grains (57'2 grammes), and 251-6 

 grains (16'28 grammes). The proportion of undigested matters in the solid 

 residue was very small, averaging but little more than ten per cent., the mean 

 quantity in the twenty-four hours in ten observations being but 52'5 grains 

 (3-4 grammes). This was found, however, to be very variable ; the largest 

 quantity being 126-5 grains (8'2 grammes), and the smallest, 12-5 grains (0-81 

 gramme). 



Microscopical examination of the faeces reveals various vegetable and ani- 

 mal structures which have escaped the action of the digestive fluids. Weh- 

 sarg also found a " finely divided faecal matter " of indefinite structure, but 

 containing partly disintegrated intestinal epithelium. Crystals of cholester- 

 ine were never observed. Whenever the matter is neutral or alkaline, crys- 

 tals of ammonio-magnesian phosphate are found. Mucus is also found 

 in variable quantity in the faeces, with desquamated epithelium and a few 

 leucocytes. In addition, recent microscopical researches have shown the 

 presence of spores of yeast and a great variety of bacteria, which latter exist 

 in the faeces in great abundance. These organisms probably excite many 

 of the so-called putrefactive changes in the intestinal contents, which result 

 in the formation of indol, phenol, skatol, cresol etc. According to Senator, 



these putrefac- 

 tive products 

 do not occur in 

 the meconium. 

 The quantity 

 of inorganic 

 salts in the 

 faeces is not 

 great. In ad- 

 dition to the 



ammonio-magnesian phosphate, magnesium phosphate, calcium phosphate 

 and a small quantity of iron have been found. The chlorides are either ab- 

 sent or are present only in small quantity. 



Marcet has pretty generally found in the human faeces a substance pos- 

 sessing the characters of margaric acid, and volatile fatty acids ; the latter 

 free, however, from butyric acid. He also found a coloring matter, which is 

 probably a modification of bile-pigment. Cystine is mentioned as an occa- 

 sional constituent of the faeces. 



In addition to the matters just enumerated, the following substances have 

 been extracted from the normal faeces : 



Excretine and Excretoleic Acid. Excretine was obtained from the nor- 

 mal faeces, by Marcet, in 1854. This substance crystalizes from an ethereal 

 solution in two or three days, in the form of long, silky crystals. Examined 



Jx* 



,o C/ 



FIG. 80. Micro-organisms of the large intestine (Landois). 



1, bacterium coli commune ; 2, bacterium lactis aerogenes ; 3, 4, the large bacilli 

 of Bienstock, with partial endogenous spore-formation ; 5, the various stages of 

 the development of the bacillus which causes the fermentation of albumen. 



